The present invention is directed to arbor slitters for slitting coils of metallic or nonmetallic materials into strips of narrower width. While not intended to be so limited, the slitter of the present invention will be described in its application to a precision slitting line for coils of metallic material.
In the operation of a typical precision slitting line, a metallic coil to be slit is mounted on an appropriate payoff reel. A peeler lifts the leading end of the coiled strip from the coil and directs the strip to power feed and strip alignment means. From this last mentioned means, the strip passes through an arbor slitter and ultimately to a recoiler where the individual narrower strips formed by the slitter are recoiled. The slitter, itself, comprises a pair of parallel cooperating arbors, the ends of which are mounted in suitable bearing housings. The cooperating pair of arbors carry coacting rotary slitting knives appropriately spaced along the arbors by distances corresponding to the widths into which the strip is to be slit.
Set-up or arrangement of the slitting knives on the arbor, which normally must be very precise, is a time consuming operation. During set-up, the slitting line must be shut down. Down time for the slitting line represents a loss of valuable production time. It is not uncommon that when a number of relatively small orders are to be processed, more time is consumed in set-up than in production.
Prior art workers have taken several approaches toward the reduction of set-up time. A common approach is simply to provide two arbor slitters for the slitting line. While one arbor slitter is in the line in production, the other arbor slitter can be located in a service area where it can be appropriately set-up for the next production run. While this procedure significantly reduces down time, it requires a duplication of equipment together with additional equipment to shift the arbor slitters between the line and the service area. The substitution of one arbor slitter for another requires down time for the line even though it be less than that required if only a single arbor slitter is used.
U.S. Pat. No. 2,291,789 is representative of another prior art approach wherein pairs of cooperating arbors are mounted on a framework. The framework is rotatable about a shaft extending transversely of the slitting line. In such an arrangement, however, when one cooperating pair of arbors is in a working position, the remaining pairs of arbors are located beneath the slitting line and are not conveniently positioned for set-up.
U.S. Pat. No. 3,503,293 is exemplary of prior art attempts to provide auxiliary equipment to speed up set-up time. This reference teaches a transfer device having elements which can be brought into alignment with the working arbors to receive the old arrangement of blades to be removed from the arbors and to shift to the arbors a new arrangement of blades for the next slitting operation. Such a system still requires considerable down time for the line.
Yet another approach is illustrated in U.S. Pat. Nos. 3,727,503 and Re. 27,918 together with Italian Pat. No. 932,425. U.S. Pat. No. 3,727,503 and Italian Pat. No. 932,425 teach the provision of a plurality of cooperating pairs of arbors radially mounted on a turntable. As a result, each cooperating pair of arbors can be rotated between a working position wherein they extend transversely of the slitting line and a set-up position extending away from the slitting line. U.S. Pat. No. Re. 27,918 teaches the provision of a plurality of slitters, radially arranged and mounted on a turntable, each slitter being shiftable between a working position and a set-up position.
While these arrangements represent an advance in the art, they do have certain drawbacks. First of all, rotation of the arbor pairs (or a plurality of slitters as in U.S. Pat. No. Re. 27,918) describes a large circular envelope requiring considerable room. This envelope also overlies the feed and strip alignment mechanism ahead of the slitter in the slitting line and therefore this equipment must also be shiftable, collapsible or otherwise movable out of the envelope during change over from one arbor pair to another. Such movement of the feed and alignment mechanism is in itself time consuming and difficult in that the positioning of the feed and alignment mechanism is critical in the slitting line.
The present invention is directed to a slitter having a supporting framework comprising a first portion extending transversely of the slitting line and a second extended portion located at the inboard end of the first portion. Two or more pairs of cooperating arbors are supported at their inboard ends by inboard bearing housings, all of which are mounted on a common base. The base is provided with caster means and is free to both shift along and reorient on the upper surface of the second extended portion of the slitter frame. The outboard end of the first portion of the slitter frame carries an outboard bearing housing which is engageable with any one of the arbors pairs when that arbor pair is in its working position. By this arrangement, the arbor pairs can be shifted and reoriented between working and set-up positions and this shifting and orienting defines an envelope which does not interfere with the feed and strip alignment mechanism of the slitting line. As will be described hereinafter, the envelope can be modified so as to avoid other obstacles or mechanisms near the slitting line, giving greater freedom of location for the slitting line. Change-over from one pair of arbors to another can be accomplished by manually operated controls or in a fully automated manner, as will be described.